Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95636C433EF for ; Mon, 20 Dec 2021 15:03:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239024AbhLTPDu (ORCPT ); Mon, 20 Dec 2021 10:03:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240270AbhLTPAI (ORCPT ); Mon, 20 Dec 2021 10:00:08 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3562DC07E5F0; Mon, 20 Dec 2021 06:51:08 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C6DC8611A8; Mon, 20 Dec 2021 14:51:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A944FC36AE8; Mon, 20 Dec 2021 14:51:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1640011867; bh=/vqcRNNi4KB0azWfc2AImzJiqHf5jg6Q3+G+/1ZA1yk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LueKybgl0+ja5jIVHaUywITK27sKITZc2PJa2ipLm1d2R8tc+1xvSES3RfdLLoO4f KaAiftagM1gHlMmn+juWXRTWz2GjyKoLPt1QknwnFW61dC8lOsB6ynS82vfFWQt/Fv XeAyONpS0db+uCZij1FYtPPp0VMHbD/sI0NG70H0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miklos Szeredi , syzbot+75eab84fd0af9e8bf66b@syzkaller.appspotmail.com Subject: [PATCH 5.10 88/99] ovl: fix warning in ovl_create_real() Date: Mon, 20 Dec 2021 15:35:01 +0100 Message-Id: <20211220143032.361312573@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211220143029.352940568@linuxfoundation.org> References: <20211220143029.352940568@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi commit 1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c upstream. Syzbot triggered the following warning in ovl_workdir_create() -> ovl_create_real(): if (!err && WARN_ON(!newdentry->d_inode)) { The reason is that the cgroup2 filesystem returns from mkdir without instantiating the new dentry. Weird filesystems such as this will be rejected by overlayfs at a later stage during setup, but to prevent such a warning, call ovl_mkdir_real() directly from ovl_workdir_create() and reject this case early. Reported-and-tested-by: syzbot+75eab84fd0af9e8bf66b@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/dir.c | 3 +-- fs/overlayfs/overlayfs.h | 1 + fs/overlayfs/super.c | 12 ++++++++---- 3 files changed, 10 insertions(+), 6 deletions(-) --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -137,8 +137,7 @@ kill_whiteout: goto out; } -static int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, - umode_t mode) +int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, umode_t mode) { int err; struct dentry *d, *dentry = *newdentry; --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -519,6 +519,7 @@ struct ovl_cattr { #define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) }) +int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, umode_t mode); struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, struct ovl_cattr *attr); int ovl_cleanup(struct inode *dir, struct dentry *dentry); --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -743,10 +743,14 @@ retry: goto retry; } - work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode)); - err = PTR_ERR(work); - if (IS_ERR(work)) - goto out_err; + err = ovl_mkdir_real(dir, &work, attr.ia_mode); + if (err) + goto out_dput; + + /* Weird filesystem returning with hashed negative (kernfs)? */ + err = -EINVAL; + if (d_really_is_negative(work)) + goto out_dput; /* * Try to remove POSIX ACL xattrs from workdir. We are good if: